Machine-tool



Aug. 21, 1956 A. Youssouf-IAN ET AL 2,759,378

MACHINE-TOOL 4 Sheets-Sheet l Filed NOV. 25, 1955 Aug' 21, l956 A. Youssouf-IAN ET AL 2,759,378

MACHINE-TOOL 4 Sheets-Sheet'Z Filed Nov. 25, 1955 A118 21, 1956 A. YoussoUFlAN ET AL MACHINE-TOOL 4 Sheets-Sheet 3 Filed Nov. 25, 1955 FIG. 3

Aug- 21, 1956 A. YoUssoUFlAN ET A'. 2,759,378

MACHINE-TOOL Filed NOV. 25, 1955 4 heats-Sheet 4 United States Patent Otlice Patented Aug. 21, 1.956

MACHINE-TOOL Ara Youssoulan and Germain Rollat, Geneva, Switzerland, assignors to Societe Genevoise dlnstruments de Physique, Geneva, Switzerland, a firm of Switzerland Application November 25, 19'55, Serial No. 549,068 Claims priority, application Switzerland December 8, 1954 12 Claims. (Cl. 77-36) Our invention has for its object a machine-tool and more particularly a jig boring machine, a boring machine or a cutting machine yincluding a cross-member adapted to move vertically and over which a tool-carrying headstock is adapted to move horizontally, said crossmember being carried near each of its ends by a piston adapted to move inside a control cylinder inserted in a pump-controlled hydraulic circuit.

In a machine-tool of this type and when the headstock is located at the middle of the cross-member, the weight of the latter is distributed equally between the two pistons, but a lack of equilibrium arises when the headstock is shifted towards one of the ends of the cross-member, the corresponding piston being loaded to a greater extent and the other piston being relieved. This may result after some time in a deformation of certain parts, which .is detrimental to the accuracy of the machine.

To remove this drawback, it lhas been proposed to provide a balancing of the cross-member through a counterweight; but this .is ditiicult to achieve in practice because the vertical movements of the cross-member and the horizontal movements of the headstock require that the cable or chain connecting the headstock with the counterweight be mounted on a pivoting system of pulleys of an intricate design. On the other hand, it is difficult to constrain the traction exerted by the counter-weight to act always in the desired direction when the position of the cross-member varies.

According to another prior proposition, it is possible to make a member, the weight of which .is equal to that to the headstock, move over the same horizontal crossmember as the latter, the movements of lsaid member being equal an-d opposed to those of said headstock. The center of gravity of the system thus constituted remains unvarying whatever may be the location of the headstock. However, this leads to a considerable increase in the weight of the movable system and in its bulk.

Now, the present invention has for its object to cut out the diierent drawbacks mentioned hereinabove; according to said invention, there are provided a member for adjusting the pressure in the hydraulic circuit referred to hereinabove and a transmission system connecting said adjusting member with the headstock so that when the latter moves towards one of the ends of the cross-member, the pressure in the control 'cylinder located on the saine side increases whereas the pressure in the lother control cylinder is reduced, whereby the modifications in the weight components exerted on the pistons in the control cylinders, which modifications arise through the changes in position of the headstock, are balanced.

The accompanying drawings illustrate by way of examples two preferred embodiments of the present invention. In said drawings:

Fig. l is an elevational view of a first embodiment of the invention incorporated into a jig-horingmachine with two uprights.

Fig. 2 is a diagram illustrating the operation of the weight compensating means incorporated into said machine.

Fig. 3 is a detail cross-sectional view through a part of said machine.

Fig. 4 is an elevational view of a second embodiment of the invention incorporated into a horizontal boring machine having only one upright.

In the first embodiment illustrated more particularly in Fig. l, the machine includes a frame 1 and two uprights 2a and 2b secured to either side thereof and between which is located a table 3 sliding over slideways 4 and 5 and carrying the work. The headstock 12 is shiftably mounted on a vertically sliding cross-member 9 carried at its ends by two pistons 14 and 15 engaging the corresponding cylinders 16 and 17 which are rigid with the frame 1. lt is possible to shift the said crossmember vertically through the simultaneous rotation of two worms of which only one, 24, is illustrated. These worms are carried by a stationary cross-member 25 and their rotation is obtained by an electric motor which is not illustrated. They cooperate with two nuts rigid with the movable cross-member, 9, of which only one is .illustrated at 26 for cooperation with the worm 24.

The pumps zz, b, c, d, produce the oil pressure required for supporting and when desired shifting vertically the cross-member 9 thro-ugh the agency of the pistons 14-15 and cylinders 16-17.

The large throughput pumps b and c serve only during the rising movements of the cross-member 9 and operate consequently only in an intermittent manner.

The small throughput pumps a and d operate continuously and supply the corresponding cylinders 16 and 17 with oil under pressure acting on the pistons 14 and 15, so as to provide for the equilibrium of the cross-member 9 while making up for any losses of pressure. Said pressure is adjusted separately for each cylinder by the corresponding valves h1 and h2 in conformity with the pressure prevailing inside the pipes V1 and V2 leading to said valves.

'Ihe pressures in the two circuit pipes V1 and V2 are adjusted separately through the corresponding distributors K1 and K2 which are not illustrated in Fig. l; said distributors are arranged in parallelism and are fed through an auxiliary hydraulic circuit t fed with oil under high pressure by the pump e and provided with a discharge valve g.

The distributors K1 and K2 are controlled respectively by the pusher members 2l) and 21 in contacting relationship with the sloping surfaces 22 and 23 formed on the underside of the headstock 12 and consequently there is obtained between the cylinders 16 and 17 under the acI` tion of the valves h1 and h2 as disclosed hereinafter, a differential pressure depending on the location of the headstock with reference to the slideways on the crossmember.

Between each group of pumps a, b, or c, d, and the corresponding cylinders 16 or 17 is inserted an auxiliary cylinder m1 or m2, the part played by which will be described hereinafter.

Turning to the diagram shown in Fig. 2, it is apparent that the pusher members 20 and 21 cooperate with the sloping members 22 and 23 rigid with the headstock and acting on the distributors K1 and K2. The latter are fed by the auxiliary circuit t rand the pump e and they adjust the pressure in the pipes V1 and V2 as a fucti-'on ofthe position of the headstock.

It is essential to prevent the heat evolved in the oil body through the operation of the pumps a, b, c, d, from being transferred to the -cross-member 9 through the agency of the cylinders 16, 17 and of the pistons 14, 15.

Fig. 2 shows diagrammatically an arrangement satisfying this requirement and including the two above-mentioned stationary cylinders m1 and m2, fitted each in one of the feeding circuits between the group of pumps a-b or c-d and the corresponding cylinder 16 or 17. Each of the cylinders mtl, m2 encloses a free piston n1, n2 which is intended to form a wall as fluidtight as possible between the hot oil in the pump system and the cool oil in the cylinders 16 and 17, the oil pressure remaining equal to either side of each free piston n1 or n2.

Since the losses of oil are practically unavoidable, each of the pistons n1 and n2 is provided with valves p opening automatically when the piston reaches the end of its stroke at either end of the corresponding cylinder, so as to make up for such losses.

In Fig. 3, 9 designates again the cross-member shown cross-sectionally. The slideways 1i) serve for Acarrying and guiding the headstock 12 to which is secured a sloping member 22. The body 27 of the distributor K1 secured to the cross-member 9, forms a casing, the upper part of which is closed by a cover 28. The latter carries an inner dependingT guideway 29 inside which may be shifted vertically the pusher-member which is held against angular movement by a pin 30 engaging two diametrically opposed slots 31 in the guideway 29. Said pusher-member is provided with a roller 32 in its upper section for engagement with the sloping member 22 and it rests through its lower end on one of the arms of the lever 33 pivotally secured to a spindle 34 rigid with the body 27 of the distributor. A further pusher-member 35 acting in antagonism with the pusher-member 20 acts on the latter with the interposition of one arm of the lever 33 so as to urge the roller 32 into contacting engagement with the sloping member 22; said pusher-member 35 bears A the lever 33. The movements of the pusher-member 20 are thus transmitted positively to the piston 36 which slides inside its housing 37 so as to open or to close gradually the distributor ports 39. The pivot 34 for the lever 33 is carried on a spindle 40 which may be shifted inside a slideway 41 so as to allow a modication in the ratio between the operative lengths of the two arms of the lever 33. This modication leads to a modication in the stroke of the piston 36. The auxiliary hydraulic circuit t is connected with the distributor K1 through the port 42 opening into the upper ports of the slide valve casing 37 while the port 43 serves for connecting the pipe V1 with the lower ports 39 of said casing. The operative section of the piston 36 which cooperates with the casing ports is provided with a double bevel so that, when the piston sinks, the upper level 44 gradually connects the pipe or circuit V1 with the circuit t through the ports 42 and 43 while the lower' bevel 45 cuts off gradually the connection between the pipe or circuit V1 and the discharge 46 opening into the bottom of the casing 37.

The pressure in the auxiliary circuit l being higher than the pressure in the circuit V1 and the discharge channel 46 being at atmospheric pressure, it is possible to increase the pressure in the circuit V1 by shifting the piston 36 downwardly and, reversely, it is possible to reduce the pressure in the circuit V1 by shifting the piston 36 upwardly, this producing a connection to a varying extent between V11 on the one hand and 46 on the other hand.

The distributor K2 is altogether similar to the distributor K1 and adjusts the pressure in the circuit V2 in the manner disclosed hereinabove for the circuit V1.

Since the pressure in each of the cylinders 16 and 17 is adjusted by the valves h1 and h2 as a function of the pressure prevailing in the corresponding circuits V1 and V2, it is apparent that the equilibrium provided by said 4 cylinders 16 and 17 varies according to the location of the headstock.

The sloping surfaces 22 and 23 are arranged in a manner such that, when the headstock is shifted towards the left, the pressure increases inside the cylinder 16 and is reduced in the cylinder 17 and reversely as provided through operation of the distributor slide-valves.

The machine-tool illustrated in Figs. 1 to 3 operates as follows: when the headstock 12 moves towards the left hand side, the pusher-member 20 rises and its movement is transmitted through the lever 33 to the piston 36 in the distributor K1. The operative doubly bevelled section of said piston 36 sinks gradually and connects thus the circuit t with the pipe V1. The valve h1 closes, under the action of the increasing pressure in the latter, the opening o1 and the pump a feeds exclusively the cylinder m1, since the by-pass across said cylinder is thus closed at o1. The piston 111 moves towards the right hand side and transmits the pressure to the cylinder 16 whereby the piston 14 in the latter equilibrates the increase of the weight component acting on the said piston as provided by the movement of the headstock.

For a movement of the headstock in the opposite direction, the piston 36 in the distributing valve 37 rises and closes gradually the port 42; the circuit V1 leading to the valve h1 communicates thus with the discharge pipe 46 so that the said valve h1 is released and uncovers the opening 01 and the pressure exerted on the piston n1 is relieved through the opening of the by-pass across the cylinder m1, which leads to a reduction in pressure inside the corresponding cylinder 16. A sequence of operative steps symmetrical with reference to those which have just been described is performed simultaneously for the ports on the right hand side of the machine.

The horizontal boring machine illustrated in Fig. 4 includes a table or bed 3 located laterally and a single upright 2 provided with vertical slideways 7 and 8 along which may move the cross-member 9. The latter carries transverse slideways 10 and 11 which guide the headstock 12 in its horizontal movements. The tool-carrying spindle of said headstock is shown at 13. The cylinders 16 and 17 are no longer as precedingly rigid with the frame and rest directly on the ground. The vertical movements of the cross-member are controlled by a worm 18 driven by a motor 19 and cooperating with a nut which is not illustrated and which is rigid with the cross-member 9.

The equilibrium of the movable cross-member corresponding to the varying positions of the headstock is obtained in the same manner as in the preceding embodiment illustrated in Figs. 1 to 3.

What I claim is:

l. In a machine-tool, the combination of a cross-member, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, a pump system, a dual primary hydraulic circuit fed by the pump system and controlling the pressure in the main cylinders, dual means for adjusting the pressure at two points of said primary hydraulic circuit and means through which the headstock controls said adjusting means to make the pressure in each cylinder increase when the headstock moves towards the corresponding end of the cross-member and reversely, and to make thereby said pressure balance the modifications in the weight component acting on the corresponding piston.

2. In a machine-tool, the combination of a crossmember, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, two pumps, a primary hydraulic circuit fed by each pump and controlling the pressure in the corresponding main cylinder, two auxiliary hydraulic circuits, means feeding said auxiliary circuits and controlled by the headstock as it moves over the cross-member, two adjusting valves submitted each to the difference between the pressures prevailing in the corresponding primary and auxiliary circuits and adapted to adjust the pressure in the corresponding main cylinder to make the pressure therein balance the weight exerted thereon by the crossmember and the headstock thereon.

3. In a machine-tool, the combination of a crossmember, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, two pumps, a primary hydraulic circuit fed by each pump and controlling the pressure in the corresponding main cylinder, two auxiliary hydraulic circuits, a pump feeding the auxiliary circuits, a slide-valve controlling the pressure in each auxiliary circuit and controlled by the movements of the headstock over the cross-member, two adjusting valves submitted each to the difference between the pressure prevailing in the corresponding primary auxiliary circuits and adapted to adjust the pressure in the corresponding main cylinder to make the pressure therein balance the weight exerted thereon by the cross-member and the headstock thereon.

4. In a machine-tool, the combination of a crossmember, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, main cylinders in which each piston is adapted to move vertically, two pumps, a primary hydraulic circuit fed by each pump and controlling the pressure in the corresponding main cylinder, an auxiliary hydraulic circuit including a main section, a discharge pipe and two branch pipes, a pump feeding the main section, a slide Valve controlling the connection between the main section and each branch pipe to adjust the pressure in the latter and controlled by the movements of the headstock over the cross-member to set gradually the corresponding branch pipe in connection with the main section and out of connection with the discharge pipe and reversely, two adjusting valves submitted each to the difference between the pressures prevailing in the corresponding primary circuit and branch pipe and adapted to adjust the pressure in the corresponding main cylinder to make the pressure therein balance the weight exerted thereon by the crossmernber and the headstock thereon.

5. In a machine-tool, the combination of a cross-member, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member and provided with two longitudinal surfaces of opposite inclinations facing downwardly, a pusher-member permanently engaging the corresponding sloping surface -on the headstock, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, two pumps, a primary hydraulic circuit fed by each pump and controlling the pressure in the corresponding main cylinder, two auxiliary hydraulic circuits, a pump feeding the auxiliary circuits, a slide-valve controlling the pressure in each auxiliary circuit and controlled by the corresponding pusher-member, two adjusting valves submitted each to the difference between the pressures prevailing in the corresponding primary and auxiliary circuits and adapted to adjust the pressure in the corresponding main cylinder to make the pressure therein balance the weight exerted thereon by the cross-member and the headstock thereon.

6. In a machine-tool, the combination of a cross-member, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally yover said cross-member and provided with two longitudinal surfaces of opposite inclinations facing downwardly, a pusher-member permanently engaging the corresponding sloping surface on the headstock, a lever pivotally -secured to the cross-member and controlled by each pusher-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, two pumps, a primary hydraulic circuit fed by each pump, two auxiliary hydraulic circuits, a pump feeding the auxiliary circuits, a slide-valve lcontrolling the pressure in each auxiliary circuit and controlled by the youter end of the corresponding lever, means for adjusting the ratio between the operative arms of said lever, two adjusting valves submitted each to the difference between the pressures prevailing in the correspondeing primary and auxiliary circuits and adapted to adjust the pressure in the correspond-ing main cylinder to make the pressure therein balance the weight exerted thereon by the cross-member and the headstock.

7. In a machine-tool, the combination of a cross-member, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertlcally, two groups of pumps of different outputs, two primary hydraulic circuits fed by the corresponding groups of pumps and controlling the pressure in the main cylinders, the larger output pump in each group being adapted to shift the piston in the main corresponding cylinder and the smaller output pump in each group being adapted to provide a steady weight-balancing pressure in the corresponding main cylinder and to compensate for fluid losses, means for adjusting the pressure in each primary circuit, and means through which the headstock controls said adjusting means to make the pressure in each cylinder increase when the headstock moves towards the corresponding end of the cross-member and reversely, and to make thereby said pressure balance the modifications in the weight component acting on the corresponding piston.

8. In a machine-tool, the combination of a cross-member, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over. said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, a pump system, a dual primary hydraulic circuit fed by the pump system and controlling the pressure in the main cylinders, an auxiliary cylinder inserted in a section of the primary circuit between the pump system and each cylinder, an auxiliary piston adapted to move inside said auxiliary cylinder to separate the fluid masses in said section of the primary circuit respectively on the side leading to the corresponding cylinder and on the side leading to the pump system, dual means for adjusting the pressure on the pump side of each of said sections of said primary hydraulic circuit and means through which the headstock controls said adjusting means to make the pressure in each cylinder increase when the head-stock moves towards the corresponding end of the cross-member and reversely, and to make thereby said pressure balance the modifications in the weight component acting on the corresponding piston.

9. In a machine-tool, the combination of a cross-member, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, a pump system, a dual primary hydraulic circuit fed by the pump system and controlling the pressure in the main cylinders, an auxiliary cylinder inserted in a section of each primary circuit between the pump system and each cylinder, an auxiliary piston adapted to move inside said auxiliary cylinder to separate the iiuid masses in said section of the primary circuit respectively on the side leading to the corresponding cylinder and on the side leading to the pump system, each auxiliary piston being provided with transverse ports, valves controlling the ports extending through each auxiliary piston to provide for a compensation `of the losses of fluid when the piston has reached an end of its stroke, dual means for adjusting the pressure on the pump side of each of said sections of said primary hydraulic circuit and means through which the headstock controls said adjusting means to make the pressure in each cylinder increase when the head-stock moves towards the corresponding end of the cross-member and reversely, and to make thereby said pressure balance the modifications in the weight component acting on the corresponding piston.

l0. In a machine-tool, the combination of a crossmember, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, a pump system, two primary hydraulic circuits :fed by the pump system and controlling the pressure in the main corresponding cylinders, a by-pass adapted to reduce the pressure in each primary circuit, a valve controlling said by-pass, an auxiliary hydraulic circuit including a main section, a discharge pipe and two branch pipes leading each to one of said valves, a pump feeding said main section, a slide valve controlling the connection between the main section and each branch pipe and thereby the pressure exerted by the latter on the corresponding by pass controlling valve to make the latter relieve to a varying extent the pressure in the corresponding main cylinder and means wherethrough the headstock controls the slide valves as it moves over the cross-member to make the pressure in the main cylinders increase as said headstock moves nearer same.

1l. 1n a machine-tool, the combination of a crossmember, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, and provided with two longitudinal surfaces of opposite inclinations facing downwardly, a pusher-member permanently engaging the corresponding sloping surface on the headstock, a lever pivotally secured to the cross-member and controlled by each pusher-member, a piston carrying each of the cross-members, main cylinders in which each piston is adapted to move vertically, a pump system, two primary hydraulic circuits fed by the pump system and controlling the pressure in the corresponding main cylinders, a by-pass adapted to reduce the pressure in each primary circuit, a valve controlling said by-pass, an

auxiliary hydraulic circuit including a main section, a discharge pipe and two branch pipes leading each to one of said valves, a pump feeding said main section, a slide valve controlled by the outer end of the corresponding lever, and controlling the connection between the main section and each branch pipe and thereby the pressure exerted through the latter on the corresponding by-pass controlling valve to make the latter relieve to a varying extent the pressure in the corresponding main cylinder.

l2. ln a machine-tool, the combination of a crossmember, an upright system over which said cross-member is adapted to move vertically, a tool-carrying headstock adapted to move horizontally over said cross-member, a piston carrying each end of the cross-member, main cylinders in which each piston is adapted to move vertically, a pump system, two primary hydraulic circuits fed by the pump system and controlling the pressure in the corresponding main cylinders, a by-pass adapted to reduce the pressure in each primary circuit, a valve controlling said by-pass, an auxiliary cylinder inserted in a section of each primary circuit between the pump system and each cylinder, an auxiliary piston adapted to move inside ysaid auxiliary cylinder to separate the fluid masses in said section of the primary circuit respectively on the side leading to the corresponding cylinder and on the side leading to the pump system, each auxiliary piston being provided with transverse ports, valves controlling the ports extending through each auxiliary piston to provide for a compensation of the losses of fluid when the piston had reached an end of its stroke, an auxiliary hydraulic circuit including a main section, a discharge pipe and two branch pipes leading each to one of the by-pass controlling valves, a pump feeding said main section, a slide valve controlling the connection between the main section and each branch pipe and thereby the pressure exerted by the latter on the corresponding by-pass controlling valve to make the latter relieve to a varying extent the pressure in the corresponding main cylinder and means wherethrough the headstock controls the slide valves as it moves over the cross-member to make the pressure in the main cylinders increase as said headstock moves nearer same.

References Cited in the file of this patent UNITED STATES PATENTS 

